Systems and methods for facilitating virtualization of a heterogeneous processor pool

ABSTRACT

A system for facilitating virtualization of a heterogeneous processor pool includes a processor allocation component and a hypervisor, each executing on a host computer. The processor allocation component identifies a plurality of physical processors available for computing and determines a set of flags, each of the set of flags identifying a type of functionality provided by each of a subset of the plurality of physical processors. The hypervisor, in communication with the processor allocation component, allocates, to at least one virtual machine, access to one of the subset of the plurality of physical processors.

RELATED APPLICATIONS

This application claims priority to, and is a continuation of, U.S.patent application Ser. No. 12/325,710, titled “Systems and Methods forFacilitating Virtualization of a Heterogeneous Processor Pool,” filedDec. 1, 2008, which issued as U.S. Pat. No. 8,352,952 on Jan. 8, 2013,and which is incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

This disclosure generally relates to systems and methods forvirtualizing physical resources provided by a computing device. Inparticular, this disclosure relates to systems and methods forfacilitating virtualization of a heterogeneous processor pool.

BACKGROUND OF THE DISCLOSURE

In conventional computing environments implementing a hypervisor toexecute a virtual machine on a host computing device, the hypervisor mayprovide the virtual machine with access to hardware resources providedby at least one physical computing device. The hypervisor may allocatephysical resources from a pool of physical computing devices, which mayinclude heterogeneous processors providing different levels offunctionality. In some environments, a hypervisor may need to migrate avirtual machine from one physical computing device to a second physicalcomputing device; for example, when the first physical computing devicerequires maintenance or no longer has the capacity to provide thevirtual machine with the allocated hardware resources. In the event thatthe two physical computing devices provide different functionality—forexample, heterogeneous processor functionality—the migration of thevirtual machine from the first physical computing device to the secondmay fail. For example, the virtual machine may execute a processrequiring access to functionality provided by the first physicalcomputing device but not by the second and a migration of the virtualmachine may result in unanticipated execution errors or undesiredtermination of the virtual machine.

Conventional solutions to this problem typically involve providinghomogeneous functionality in the pool of physical computing devices.However, this approach typically limits an administrator's ability toprovide a diverse range of functionality for users. Furthermore, asphysical resources age and require replacement, administrators may notbe able to find replacement devices that provide identicalfunctionality.

BRIEF SUMMARY OF THE DISCLOSURE

In one aspect, a method for facilitating virtualization of aheterogeneous processor pool includes identifying a plurality ofphysical processors available for computing. The method includesdetermining a set of flags, each of the set of flags identifying a typeof functionality provided by each of a subset of the plurality ofphysical processors. The method includes allocating, by a hypervisor toat least one virtual machine, access to one of the subset of theplurality of physical processors. In one embodiment, the method includesproviding, by a hypervisor, a virtual processor in the at least onevirtual machine, the virtual processor implementing only functionalityidentified by the set of flags. In another embodiment, the methodincludes determining, in response to a command received from a user, theset of flags.

In another aspect, a system for facilitating virtualization of aheterogeneous processor pool includes a processor allocation componentand a hypervisor, each executing on a host computer. The processorallocation component identifies a plurality of physical processorsavailable for computing and determining a set of flags, each of the setof flags identifying a type of functionality provided by each of asubset of the plurality of physical processors, the processor allocationcomponent executing on a host computer. The hypervisor executes on thehost computer and, in communication with the processor allocationcomponent, allocates, to at least one virtual machine, access to one ofthe subset of the plurality of physical processors. In one embodiment,the plurality of physical processors is distributed across a pluralityof physical machines. In another embodiment, the system includes avirtual processor, within the at least one virtual machine, the virtualprocessor implementing only functionality identified by the set offlags.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects, features, and advantages ofthe disclosure will become more apparent and better understood byreferring to the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1A is a block diagram depicting an embodiment of a computingenvironment comprising a hypervisor layer, a virtualization layer, and ahardware layer;

FIGS. 1B and 1C are block diagrams depicting embodiments of computingdevices useful in connection with the methods and systems describedherein;

FIG. 2A is a block diagram depicting an embodiment of a system forfacilitating virtualization of a heterogeneous processor pool;

FIG. 2B is a block diagram depicting an embodiment of a system forfacilitating virtualization of a heterogeneous processor pool providedby a plurality of physical computing devices;

FIG. 2C is a block diagram depicting an embodiment of a system forfacilitating virtualization of a heterogeneous processor pool providedby a plurality of physical computing devices including a mastercomputing device; and

FIG. 3 is a flow diagram depicting an embodiment of a method forfacilitating virtualization of a heterogeneous processor pool.

DETAILED DESCRIPTION

Referring now to FIG. 1A, a block diagram depicts one embodiment of avirtualization environment. In brief overview, a computing device 100includes a hypervisor layer, a virtualization layer, and a hardwarelayer. The hypervisor layer includes a hypervisor 101 (also referred toas a virtualization manager) that allocates and manages access to anumber of physical resources in the hardware layer (e.g., theprocessor(s) 221, and disk(s) 228) by at least one virtual machineexecuting in the virtualization layer. The virtualization layer includesat least one operating system 110 and a plurality of virtual resourcesallocated to the at least one operating system 110, which may include aplurality of virtual processors 132 a, 132 b, 132 c (generally 132),and/or virtual disks 142 a, 142 b, 142 c (generally 142). The pluralityof virtual resources and the operating system 110 may be referred to asa virtual machine 106. A virtual machine 106 may include a controloperating system 105 in communication with the hypervisor 101 and usedto execute applications for managing and configuring other virtualmachines on the computing device 100.

Referring now to FIG. 1A, and in greater detail, a hypervisor 101 mayprovide virtual resources to an operating system in any manner whichsimulates the operating system having access to a physical device. Ahypervisor 101 may provide virtual resources to any number of guestoperating systems 110 a, 110 b (generally 110). In some embodiments, acomputing device 100 executes one or more types of hypervisors. In theseembodiments, hypervisors may be used to emulate virtual hardware,partition physical hardware, virtualize physical hardware, and executevirtual machines that provide access to computing environments.Hypervisors may include those manufactured by VMWare, Inc., of PaloAlto, Calif.; the XEN hypervisor, an open source product whosedevelopment is overseen by the open source Xen.org community; HyperV,VirtualServer or virtual PC hypervisors provided by Microsoft, orothers. In some embodiments, a computing device 100 executing ahypervisor which creates a virtual machine platform on which guestoperating systems may execute is referred to as a host server. In one ofthese embodiments, for example, the computing device 100 is a XEN SERVERprovided by Citrix Systems, Inc., of Fort Lauderdale, Fla.

In some embodiments, a hypervisor 101 executes within an operatingsystem executing on a computing device. In one of these embodiments, acomputing device executing an operating system and a hypervisor 101 maybe said to have a host operating system (the operating system executingon the computing device), and a guest operating system (an operatingsystem executing within a computing resource partition provided by thehypervisor 101). In other embodiments, a hypervisor 101 interactsdirectly with hardware on a computing device, instead of executing on ahost operating system. In one of these embodiments, the hypervisor 101may be said to be executing on “bare metal,” referring to the hardwarecomprising the computing device.

In some embodiments, a hypervisor 101 may create a virtual machine 106a-c (generally 106) in which an operating system 110 executes. In one ofthese embodiments, for example, the hypervisor 101 loads a virtualmachine image to create a virtual machine 106. In another of theseembodiments, the hypervisor 101 executes an operating system 110 withinthe virtual machine 106. In still another of these embodiments, thevirtual machine 106 executes an operating system 110.

In some embodiments, the hypervisor 101 controls processor schedulingand memory partitioning for a virtual machine 106 executing on thecomputing device 100. In one of these embodiments, the hypervisor 101controls the execution of at least one virtual machine 106. In anotherof these embodiments, the hypervisor 101 presents at least one virtualmachine 106 with an abstraction of at least one hardware resourceprovided by the computing device 100. In other embodiments, thehypervisor 101 controls whether and how physical processor capabilitiesare presented to the virtual machine 106.

A control operating system 105 may execute at least one application formanaging and configuring the guest operating systems. In one embodiment,the control operating system 105 may execute an administrativeapplication, such as an application including a user interface providingadministrators with access to functionality for managing the executionof a virtual machine, including functionality for executing a virtualmachine, terminating an execution of a virtual machine, or identifying atype of physical resource for allocation to the virtual machine. Inanother embodiment, the hypervisor 101 executes the control operatingsystem 105 within a virtual machine 106 created by the hypervisor 101.In still another embodiment, the control operating system 105 executesin a virtual machine 106 that is authorized to directly access physicalresources on the computing device 100.

In one embodiment, the control operating system 105 executes in avirtual machine 106 that is authorized to interact with at least oneguest operating system 110. In another embodiment, a guest operatingsystem 110 communicates with the control operating system 105 via thehypervisor 101 in order to request access to a disk or a network. Instill another embodiment, the guest operating system 110 and the controloperating system 105 may communicate via a communication channelestablished by the hypervisor 101, such as, for example, via a pluralityof shared memory pages made available by the hypervisor 101.

In some embodiments, the control operating system 105 includes a networkback-end driver for communicating directly with networking hardwareprovided by the computing device 100. In one of these embodiments, thenetwork back-end driver processes at least one virtual machine requestfrom at least one guest operating system 110. In other embodiments, thecontrol operating system 105 includes a block back-end driver forcommunicating with a storage element on the computing device 100. In oneof these embodiments, the block back-end driver reads and writes datafrom the storage element based upon at least one request received from aguest operating system 110.

In one embodiment, the control operating system 105 includes a toolsstack 104. In another embodiment, a tools stack 104 providesfunctionality for interacting with the hypervisor 101, communicatingwith other control operating systems 105 (for example, on a secondcomputing device 100 b), or managing virtual machines 106 b, 106 c onthe computing device 100. In another embodiment, the tools stack 104includes customized applications for providing improved managementfunctionality to an administrator of a virtual machine farm. In someembodiments, at least one of the tools stack 104 and the controloperating system 105 include a management API that provides an interfacefor remotely configuring and controlling virtual machines 106 running ona computing device 100. In other embodiments, the control operatingsystem 105 communicates with the hypervisor 101 through the tools stack104.

In one embodiment, the hypervisor 101 executes a guest operating system110 within a virtual machine 106 created by the hypervisor 101. Inanother embodiment, the guest operating system 110 provides a user ofthe computing device 100 with access to resources within a computingenvironment. In still another embodiment, a resource includes a program,an application, a document, a file, a plurality of applications, aplurality of files, an executable program file, a desktop environment, acomputing environment, or other resource made available to a user of thecomputing device 100. In yet another embodiment, the resource may bedelivered to the computing device 100 via a plurality of access methodsincluding, but not limited to, conventional installation directly on thecomputing device 100, delivery to the computing device 100 via a methodfor application streaming, delivery to the computing device 100 ofoutput data generated by an execution of the resource on a secondcomputing device 100′ and communicated to the computing device 100 via apresentation layer protocol, delivery to the computing device 100 ofoutput data generated by an execution of the resource via a virtualmachine executing on a second computing device 100′, or execution from aremovable storage device connected to the computing device 100, such asa USB device, or via a virtual machine executing on the computing device100 and generating output data. In some embodiments, the computingdevice 100 transmits output data generated by the execution of theresource to another computing device 100′.

In one embodiment, the guest operating system 110, in conjunction withthe virtual machine on which it executes, forms a fully-virtualizedvirtual machine which is not aware that it is a virtual machine; such amachine may be referred to as a “Domain U HVM (Hardware Virtual Machine)virtual machine”. In another embodiment, a fully-virtualized machineincludes software emulating a Basic Input/Output System (BIOS) in orderto execute an operating system within the fully-virtualized machine. Instill another embodiment, a fully-virtualized machine may include adriver that provides functionality by communicating with the hypervisor101; in such an embodiment, the driver is typically aware that itexecutes within a virtualized environment.

In another embodiment, the guest operating system 110, in conjunctionwith the virtual machine on which it executes, forms a paravirtualizedvirtual machine, which is aware that it is a virtual machine; such amachine may be referred to as a “Domain U PV virtual machine”. Inanother embodiment, a paravirtualized machine includes additionaldrivers that a fully-virtualized machine does not include. In stillanother embodiment, the paravirtualized machine includes the networkback-end driver and the block back-end driver included in a controloperating system 105, as described above

The computing device 100 may be deployed as and/or executed on any typeand form of computing device, such as a computer, network device orappliance capable of communicating on any type and form of network andperforming the operations described herein. FIGS. 1B and 1C depict blockdiagrams of a computing device 100 useful for practicing an embodimentof methods and systems described herein. As shown in FIGS. 1B and 1C, acomputing device 100 includes a central processing unit 121, and a mainmemory unit 122. As shown in FIG. 1B, a computing device 100 may includea storage device 128, an installation device 116, a network interface118, an I/O controller 123, display devices 124 a-124 n, a keyboard 126and a pointing device 127, such as a mouse. The storage device 128 mayinclude, without limitation, an operating system, software, and a clientagent 120. As shown in FIG. 1C, each computing device 100 may alsoinclude additional optional elements, such as a memory port 103, abridge 170, one or more input/output devices 130 a-130 n (generallyreferred to using reference numeral 130), and a cache memory 140 incommunication with the central processing unit 121.

The central processing unit 121 is any logic circuitry that responds toand processes instructions fetched from the main memory unit 122. Insome embodiments, the central processing unit 121 is provided by amicroprocessor unit, such as: those manufactured by Intel Corporation ofMountain View, Calif.; those manufactured by Motorola Corporation ofSchaumburg, Ill.; those manufactured by Transmeta Corporation of SantaClara, Calif.; the RS/6000 processor, those manufactured byInternational Business Machines of White Plains, N.Y.; or thosemanufactured by Advanced Micro Devices of Sunnyvale, Calif. Thecomputing device 100 may be based on any of these processors, or anyother processor capable of operating as described herein.

Main memory unit 122 may be one or more memory chips capable of storingdata and allowing any storage location to be directly accessed by themicroprocessor 121, such as Static random access memory (SRAM), BurstSRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM),Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended DataOutput DRAM (EDO DRAM), Burst Extended Data Output DRAM (BEDO DRAM),synchronous DRAM (SDRAM), JEDEC SRAM, PC100 SDRAM, Double Data RateSDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM),Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM). The mainmemory 122 may be based on any of the above described memory chips, orany other available memory chips capable of operating as describedherein. In the embodiment shown in FIG. 1B, the processor 121communicates with main memory 122 via a system bus 150 (described inmore detail below). FIG. 1C depicts an embodiment of a computing device100 in which the processor communicates directly with main memory 122via a memory port 103. For example, in FIG. 1C the main memory 122 maybe DRDRAM.

FIG. 1C depicts an embodiment in which the main processor 121communicates directly with cache memory 140 via a secondary bus,sometimes referred to as a backside bus. In other embodiments, the mainprocessor 121 communicates with cache memory 140 using the system bus150. Cache memory 140 typically has a faster response time than mainmemory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In theembodiment shown in FIG. 1C, the processor 121 communicates with variousI/O devices 130 via a local system bus 150. Various buses may be used toconnect the central processing unit 121 to any of the I/O devices 130,including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannelArchitecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or aNuBus. For embodiments in which the I/O device is a video display 124,the processor 121 may use an Advanced Graphics Port (AGP) to communicatewith a display device 124. FIG. 1C depicts an embodiment of a computer100 in which the main processor 121 communicates directly with I/Odevice 130 b via HYPERTRANSPORT, RAPIDIO, or INFINIBAND communicationstechnology. FIG. 1C also depicts an embodiment in which local busses anddirect communication are mixed: the processor 121 communicates with I/Odevice 130 a using a local interconnect bus while communicating with I/Odevice 130 b directly.

A wide variety of I/O devices 130 a-130 n may be present in thecomputing device 100. Input devices include keyboards, mice, trackpads,trackballs, microphones, dials, and drawing tablets. Output devicesinclude video displays, speakers, inkjet printers, laser printers, anddye-sublimation printers. The I/O devices may be controlled by an I/Ocontroller 123 as shown in FIG. 1B. The I/O controller may control oneor more I/O devices such as a keyboard 126 and a pointing device 127,e.g., a mouse or optical pen. Furthermore, an I/O device may alsoprovide storage and/or an installation medium 116 for the computingdevice 100. In still other embodiments, the computing device 100 mayprovide USB connections (not shown) to receive handheld USB storagedevices such as the USB Flash Drive line of devices manufactured byTwintech Industry, Inc., of Los Alamitos, Calif.

Referring again to FIG. 1B, the computing device 100 may support anysuitable installation device 116, such as a floppy disk drive forreceiving floppy disks such as 3.5-inch, 5.25-inch disks or ZIP disks, aCD-ROM drive, a CD-R/RW drive, a DVD-ROM drive, a flash memory drive,tape drives of various formats, USB device, hard-drive or any otherdevice suitable for installing software and programs. The computingdevice 100 may further comprise a storage device, such as one or morehard disk drives or redundant arrays of independent disks, for storingan operating system and other related software, and for storingapplication software programs such as any program related to the clientagent 120. Optionally, any of the installation devices 116 could also beused as the storage device. Additionally, the operating system and thesoftware can be run from a bootable medium, for example, a bootable CD,such as KNOPPIX, a bootable CD for GNU/Linux that is available as aGNU/Linux distribution from knoppix.net.

Furthermore, the computing device 100 may include a network interface118 to interface to the network 104 through a variety of connectionsincluding, but not limited to, standard telephone lines, LAN or WANlinks (e.g., 802.11, T1, T3, 56 kb, X.25, SNA, DECNET), broadbandconnections (e.g., ISDN, Frame Relay, ATM, Gigabit Ethernet,Ethernet-over-SONET), wireless connections, or some combination of anyor all of the above. Connections can be established using a variety ofcommunication protocols (e.g., TCP/IP, IPX, SPX, NetBIOS, Ethernet,ARCNET, SONET, SDH, Fiber Distributed Data Interface (FDDI), RS232, IEEE802.11, IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, CDMA, GSM, WiMax anddirect asynchronous connections). In one embodiment, the computingdevice 100 communicates with other computing devices 100′ via any typeand/or form of gateway or tunneling protocol such as Secure Socket Layer(SSL) or Transport Layer Security (TLS), or the Citrix Gateway Protocolmanufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla. The networkinterface 118 may comprise a built-in network adapter, network interfacecard, PCMCIA network card, card bus network adapter, wireless networkadapter, USB network adapter, modem or any other device suitable forinterfacing the computing device 100 to any type of network capable ofcommunication and performing the operations described herein.

In some embodiments, the computing device 100 may comprise or beconnected to multiple display devices 124 a-124 n, which each may be ofthe same or different type and/or form. As such, any of the I/O devices130 a-130 n and/or the I/O controller 123 may comprise any type and/orform of suitable hardware, software, or combination of hardware andsoftware to support, enable or provide for the connection and use ofmultiple display devices 124 a-124 n by the computing device 100. Forexample, the computing device 100 may include any type and/or form ofvideo adapter, video card, driver, and/or library to interface,communicate, connect or otherwise use the display devices 124 a-124 n.In one embodiment, a video adapter may comprise multiple connectors tointerface to multiple display devices 124 a-124 n. In other embodiments,the computing device 100 may include multiple video adapters, with eachvideo adapter connected to one or more of the display devices 124 a-124n. In some embodiments, any portion of the operating system of thecomputing device 100 may be configured for using multiple displays 124a-124 n. In other embodiments, one or more of the display devices 124a-124 n may be provided by one or more other computing devices, such ascomputing devices 100 a and 100 b connected to the computing device 100,for example, via a network. These embodiments may include any type ofsoftware designed and constructed to use another computer's displaydevice as a second display device 124 a for the computing device 100.One ordinarily skilled in the art will recognize and appreciate thevarious ways and embodiments that a computing device 100 may beconfigured to have multiple display devices 124 a-124 n.

In further embodiments, an I/O device 130 may be a bridge between thesystem bus 150 and an external communication bus, such as a USB bus, anApple Desktop Bus, an RS-232 serial connection, a SCSI bus, a FireWirebus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, a GigabitEthernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, a SuperHIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus, aSerial Attached small computer system interface bus, or a HDMI bus.

A computing device 100 of the sort depicted in FIGS. 1B and 1C typicallyoperates under the control of operating systems, which controlscheduling of tasks and access to system resources. The computing device100 can be running any operating system such as any of the versions ofthe MICROSOFT WINDOWS operating systems, the different releases of theUnix and Linux operating systems, any version of the MAC OS forMacintosh computers, any embedded operating system, any real-timeoperating system, any open source operating system, any proprietaryoperating system, any operating systems for mobile computing devices, orany other operating system capable of running on the computing deviceand performing the operations described herein. Typical operatingsystems include, but are not limited to: WINDOWS 3.x, WINDOWS 95,WINDOWS 98, WINDOWS 2000, WINDOWS NT 3.51, WINDOWS NT 4.0, WINDOWS CE,WINDOWS MOBILE, WINDOWS XP, and WINDOWS VISTA, all of which aremanufactured by Microsoft Corporation of Redmond, Wash.; MAC OS,manufactured by Apple Computer of Cupertino, Calif.; OS/2, manufacturedby International Business Machines of Armonk, N.Y.; and Linux, afreely-available operating system distributed by Caldera Corp. of SaltLake City, Utah, or any type and/or form of a Unix operating system,among others.

The computer system 100 can be any workstation, telephone, desktopcomputer, laptop or notebook computer, server, handheld computer, mobiletelephone or other portable telecommunications device, media playingdevice, a gaming system, mobile computing device, or any other typeand/or form of computing, telecommunications or media device that iscapable of communication. The computer system 100 has sufficientprocessor power and memory capacity to perform the operations describedherein. For example, the computer system 100 may comprise a device ofthe IPOD family of devices manufactured by Apple Computer of Cupertino,Calif., a PLAYSTATION 2, PLAYSTATION 3, or PERSONAL PLAYSTATION PORTABLE(PSP) device manufactured by the Sony Corporation of Tokyo, Japan, aNINTENDO DS, NINTENDO GAMEBOY, NINTENDO GAMEBOY ADVANCED or NINTENDOREVOLUTION device manufactured by Nintendo Co., Ltd., of Kyoto, Japan,or an XBOX or XBOX 360 device manufactured by the Microsoft Corporationof Redmond, Wash.

In some embodiments, the computing device 100 may have differentprocessors, operating systems, and input devices consistent with thedevice. For example, in one embodiment, the computing device 100 is aTREO 180, 270, 600, 650, 680, 700p, 700w, or 750 smart phonemanufactured by Palm, Inc. In some of these embodiments, the TREO smartphone is operated under the control of the PalmOS operating system andincludes a stylus input device as well as a five-way navigator device.

In other embodiments, the computing device 100 is a mobile device, suchas a JAVA-enabled cellular telephone or personal digital assistant(PDA), such as the i55sr, i58sr, i85s, i88s, i90c, i95cl, or the im1100,all of which are manufactured by Motorola Corp. of Schaumburg, Ill., the6035 or the 7135, manufactured by Kyocera of Kyoto, Japan, or the i300or i330, manufactured by Samsung Electronics Co., Ltd., of Seoul, Korea.In some embodiments, the computing device 100 is a mobile devicemanufactured by Nokia of Finland, or by Sony Ericsson MobileCommunications AB of Lund, Sweden.

In still other embodiments, the computing device 100 is a Blackberryhandheld or smart phone, such as the devices manufactured by Research InMotion Limited, including the Blackberry 7100 series, 8700 series, 7700series, 7200 series, the Blackberry 7520, or the Blackberry Pearl 8100.In yet other embodiments, the computing device 100 is a smart phone,Pocket PC, Pocket PC Phone, or other handheld mobile device supportingMicrosoft Windows Mobile Software. Moreover, the computing device 100can be any workstation, desktop computer, laptop or notebook computer,server, handheld computer, mobile telephone, any other computer, orother form of computing or telecommunications device that is capable ofcommunication and that has sufficient processor power and memorycapacity to perform the operations described herein.

In some embodiments, the computing device 100 is a digital audio player.In one of these embodiments, the computing device 100 is a digital audioplayer such as the Apple IPOD, IPOD Touch, IPOD NANO, and IPOD SHUFFLElines of devices, manufactured by Apple Computer of Cupertino, Calif. Inanother of these embodiments, the digital audio player may function asboth a portable media player and as a mass storage device. In otherembodiments, the computing device 100 is a digital audio player such asthe DigitalAudioPlayer Select MP3 players, manufactured by SamsungElectronics America, of Ridgefield Park, N.J., or the Motorola m500 orm25 Digital Audio Players, manufactured by Motorola Inc. of Schaumburg,Ill. In still other embodiments, the computing device 100 is a portablemedia player, such as the ZEN VISION W, the ZEN VISION series, the ZENPORTABLE MEDIA CENTER devices, or the Digital MP3 line of MP3 players,manufactured by Creative Technologies Ltd. In yet other embodiments, thecomputing device 100 is a portable media player or digital audio playersupporting file formats including, but not limited to, MP3, WAV,M4A/AAC, WMA Protected AAC, RIFF, Audible audiobook, Apple Losslessaudio file formats and .mov, .m4v, and .mp4 MPEG-4 (H.264/MPEG-4 AVC)video file formats.

In some embodiments, the computing device 100 includes a combination ofdevices, such as a mobile phone combined with a digital audio player orportable media player. In one of these embodiments, the computing device100 is a smartphone, for example, an iPhone manufactured by AppleComputer, or a Blackberry device, manufactured by Research In MotionLimited. In yet another embodiment, the computing device 100 is a laptopor desktop computer equipped with a web browser and a microphone andspeaker system, such as a telephony headset. In these embodiments, thecomputing devices 100 are web-enabled and can receive and initiate phonecalls. In other embodiments, the communications device 100 is a MotorolaRAZR or Motorola ROKR line of combination digital audio players andmobile phones.

A computing device 100 may be a file server, application server, webserver, proxy server, appliance, network appliance, gateway, applicationgateway, gateway server, virtualization server, deployment server, SSLVPN server, or firewall. In some embodiments, a computing device 100provides a remote authentication dial-in user service, and is referredto as a RADIUS server. In other embodiments, a computing device 100 mayhave the capacity to function as either an application server or as amaster application server. In still other embodiments, a computingdevice 100 is a blade server.

In one embodiment, a computing device 100 may include an ActiveDirectory. The computing device 100 may be an application accelerationappliance. For embodiments in which the computing device 100 is anapplication acceleration appliance, the computing device 100 may providefunctionality including firewall functionality, application firewallfunctionality, or load balancing functionality. In some embodiments, thecomputing device 100 comprises an appliance such as one of the line ofappliances manufactured by the Citrix Application Networking Group, ofSan Jose, Calif., or Silver Peak Systems, Inc., of Mountain View,Calif., or of Riverbed Technology, Inc., of San Francisco, Calif., or ofF5 Networks, Inc., of Seattle, Wash., or of Juniper Networks, Inc., ofSunnyvale, Calif.

In other embodiments, a computing device 100 may be referred to as aclient node, a client machine, an endpoint node, or an endpoint. In someembodiments, a client 100 has the capacity to function as both a clientnode seeking access to resources provided by a server and as a servernode providing access to hosted resources for other clients.

In some embodiments, a first, client computing device 100 a communicateswith a second, server computing device 100 b. In one embodiment, theclient communicates with one of the computing devices 100 in a farm 38.Over the network, the client can, for example, request execution ofvarious applications hosted by the computing devices 100 in the farm 38and receive output data of the results of the application execution fordisplay. In one embodiment, the client executes a program neighborhoodapplication to communicate with a computing device 100 in a farm 38.

A computing device 100 may execute, operate or otherwise provide anapplication, which can be any type and/or form of software, program, orexecutable instructions such as any type and/or form of web browser,web-based client, client-server application, a thin-client computingclient, an ActiveX control, or a Java applet, or any other type and/orform of executable instructions capable of executing on the computingdevice 100. In some embodiments, the application may be a server-basedor a remote-based application executed on behalf of a user of a firstcomputing device by a second computing device. In other embodiments, thesecond computing device may display output data to the first, clientcomputing device using any thin-client or remote-display protocol, suchas the Independent Computing Architecture (ICA) protocol manufactured byCitrix Systems, Inc. of Ft. Lauderdale, Fla.; the Remote DesktopProtocol (RDP) manufactured by the Microsoft Corporation of Redmond,Wash.; the X11 protocol; the Virtual Network Computing (VNC) protocol,manufactured by AT&T Bell Labs; the SPICE protocol, manufactured byQumranet, Inc., of Sunnyvale, Calif., USA, and of Raanana, Israel; theNet2Display protocol, manufactured by VESA, of Milpitas, Calif.; thePC-over-IP protocol, manufactured by Teradici Corporation, of Burnaby,B.C.; the TCX protocol, manufactured by Wyse Technology, Inc., of SanJose, Calif.; the THINC protocol developed by Columbia University in theCity of New York, of New York, N.Y.; or the Virtual-D protocolsmanufactured by Desktone, Inc., of Chelmsford, Mass. The application canuse any type of protocol and it can be, for example, an HTTP client, anFTP client, an Oscar client, or a Telnet client. In other embodiments,the application comprises any type of software related to voice overinternet protocol (VoIP) communications, such as a soft IP telephone. Infurther embodiments, the application comprises any application relatedto real-time data communications, such as applications for streamingvideo and/or audio.

In some embodiments, a first computing device 100 a executes anapplication on behalf of a user of a client computing device 100 b. Inother embodiments, a computing device 100 a executes a virtual machine,which provides an execution session within which applications execute onbehalf of a user or a client computing devices 100 b. In one of theseembodiments, the execution session is a hosted desktop session. Inanother of these embodiments, the computing device 100 executes aterminal services session. The terminal services session may provide ahosted desktop environment. In still another of these embodiments, theexecution session provides access to a computing environment, which maycomprise one or more of: an application, a plurality of applications, adesktop application, and a desktop session in which one or moreapplications may execute.

Referring now to FIG. 2A, a block diagram depicts one embodiment of asystem for facilitating virtualization of a heterogeneous processorpool. In brief overview, the system includes a control operating system105 executing within a virtual machine 106 a, a guest operating system110 executing within a virtual machine 106 b, a virtual CPU 132, ahypervisor 101, a processor allocation component 210, and a plurality ofphysical processors 221 a, 221 b (generally 221). The processorallocation component 210 identifies a plurality of physical processorsavailable for computing and determines a set of flags, each of the setof flags identifying a type of functionality provided by each of asubset of the plurality of physical processors, the processor allocationcomponent 210 executing on a host computer. The hypervisor 101,executing on the host computer and in communication with the processorallocation component 210, allocates, to at least one virtual machine,access to one of the subset of the plurality of physical processors. Thehypervisor 101 executes in the hypervisor layer of the computing device100. In some embodiments, the processor allocation component 210executes in the hypervisor layer of the computing device 100. In otherembodiments, the processor allocation component 210 executes on thecontrol operating system 105, in the virtualization layer of thecomputing device 100. In further embodiments, computer readable media isprovided including executable code for facilitating virtualization of aheterogeneous processor pool.

In some embodiments, the control operating system 105 identifies asubset of the functionality available from each of the plurality ofphysical processors 221. In one of these embodiments, the subset is lessthan the complete set of functionality available from at least one ofthe physical processors. In another of these embodiments, by providingthe virtual machine with a listing of functionality that is a commonsubset available across all of the physical processors, this approachensures that regardless of which of the physical processors is assignedto a virtual machine, the allocated physical processor can provide thefunctionality requested by the virtual machine. In some embodiments, theresources include physical processors 221 available for use by virtualmachines 106. In other embodiments, however, the resources may includeany resources, physical or logical, processor or otherwise, madeavailable by a computing device 100.

Referring now to FIG. 2A, and in greater detail, the processorallocation component 210 identifies a plurality of physical processorsavailable for computing and determines a set of flags, each of the setof flags identifying a type of functionality provided by each of asubset of the plurality of physical processors. In one embodiment, theprocessor allocation component 210 is a component executing within thehypervisor 101. In another embodiment, the processor allocationcomponent 210 is a component executing within the hypervisor layer andin communication with the hypervisor 101. In still another embodiment,the processor allocation component 210 is a component executing withinthe control operating system 105, which may execute within a virtualmachine 106. In yet another embodiment, the processor allocationcomponent 210 is provided as part of an enterprise managementapplications programming interface; for example, the XEN API provided aspart of a control operating system 105 in communication with a XENhypervisor, or as part of the XEN SERVER line of products provided byCitrix Systems, Inc., of Fort Lauderdale, Fla. In some embodiments, theprocessor allocation component 210 includes a receiver for receivingdata from the control operating system 105. In one of these embodiments,the control operating system 105 identifies the plurality of physicalprocessors available for computing and transmits the identification tothe processor allocation component 210. In other embodiments, the toolsstack 104 within the control operating system 105 identifies theplurality of physical processors available for computing and transmitsthe identification to the processor allocation component 210. In stillother embodiments, and as described in greater detail below inconnection with FIGS. 2B and 2C, the processor allocation component 210communicates, via the control operating system 105 and the hypervisor101, with a computing device 100 b to retrieve an identification of anavailable plurality of physical processors provided by the computingdevice 100 b.

In one embodiment, the plurality of physical processors includes aphysical processor 221. In another embodiment, the plurality of physicalprocessors includes a physical processor 121, as described above inconnection with FIG. 1B-1C. In still another embodiment, the pluralityof physical processors includes at least one microprocessor. In stilleven another embodiment, the plurality of physical processors isdistributed across a plurality of physical machines. In yet anotherembodiment, one of the plurality of physical processors supports asuperset of the determined set of flags.

A physical processor in the plurality of physical processors maintains aregister storing at least one processor flag; the register may bereferred to as a flag register or status register. A processor flag maystore an identification of functionality provided by the processor. Inone embodiment, for example, and without limitation, a flag may identifyan extension to functionality providing multimedia support provided by atype of processor, such as the “3DNOW” or “3DNOWEXT” flags identifyingthat the processor includes a multimedia extension created by AdvancedMicro Devices, Inc., (AMD) of Sunnyvale, Calif. In another embodiment,as an example, and without limitation, a flag may identify that aprocessor provides parallel execution functionality, such as the HTT/HThyper-threading flag which indicates that a processor provided by IntelCorporation of Santa Clara, Calif., provides technology to allowquasi-parallel execution of different instructions on a singleprocessor.

The hypervisor 101, executing on the host computer and in communicationwith the processor allocation component 210, allocates, to at least onevirtual machine, access to one of the subset of the plurality ofphysical processors. In some embodiments, a virtual machine provided bya hypervisor 101 queries the hypervisor 101 during an initializationprocess to identify allocated physical resources. In one of theseembodiments, the virtual machine does not typically query the hypervisor101 for the identification of allocated physical resources after theinitialization process. In another of these embodiments, a resourceexecuting within the virtual machine (such as an operating system orapplication) begins execution after the initialization process andrequests access to functionality provided by a virtual resource. Instill another of these embodiments, the virtual machine accesses anallocated physical resource in order to provide the executing resourcewith access to the requested functionality, and uses the identificationof allocated physical resources to determine whether or not therequested functionality is available. In still even another of theseembodiments, if the virtual machine has migrated to a second computingdevice after the initialization process, since the virtual machine hasnot queried the hypervisor for an update to the identification of theallocated physical resources, should the second computing device notprovide originally-identified resources, the virtual machine may attemptto provide access to functionality that is no longer available.Therefore, in some embodiments, the methods and systems described hereinallow a hypervisor 101 to provide to a virtual machine an identificationof allocated functionality that will be available regardless of whetherthe virtual machine is later migrated from a first computing device to asecond computing device, because the hypervisor 101 only identifiesfunctionality that is common across each of the plurality of computingdevices.

Referring now to FIG. 2B, a block diagram depicts an embodiment of asystem for facilitating virtualization of a heterogeneous processor poolprovided by a plurality of physical computing devices. As shown in FIG.2B, the system includes multiple computing devices 100, each of whichmakes at least one physical processor 221 available for computing. Acontrol operating system 105 a on a computing device 100 a may exchangedata with control operating system 105 b on a computing device 100 b,via communications between a hypervisor 101 a and a hypervisor 101 b. Inone embodiment, a control operating system 105 a may provide to thecontrol operating system 105 b an identification of at least onephysical processor provided by the computing device 100 a that isavailable for use by a virtual machine 106 executing on the computingdevice 100 b. In some embodiments, rather than communicate with thecontrol operating system 105 b via the hypervisors 101, the controloperating system 105 a may store an identification of available physicalprocessors in a storage element 250, which is accessible by the controloperating system 105 b. Although only two computing devices 100 a and100 b and one storage element 250 are depicted in FIG. 2B, it should beunderstood that the system may provide multiple ones of any or each ofthose components.

As described in connection with FIG. 2B, a control operating system 105a on a computing device 100 a may exchange data with control operatingsystem 105 b on a computing device 100 b, via communications between ahypervisor 101 a and a hypervisor 101 b. In this way, one or morecomputing devices 100 may exchange data with one or more of the othercomputing devices 100 regarding processors and other physical resourcesavailable in a pool of resources. In one such embodiment, each computingdevice 100 maintains data associated with each of the other computingdevices 100, including an identification of at least one physicalprocessor provided by each of the computing devices 100 that isavailable for use by a virtual machine 106 executing on anothercomputing device 100. In another embodiment, the system identifies aplurality of physical processors distributed across a plurality ofphysical machines 100.

Referring now to FIG. 2C, a block diagram depicts an embodiment of asystem for facilitating virtualization of a heterogeneous processor poolprovided by a plurality of physical computing devices including a mastercomputing device.

In some embodiments, the plurality of physical computing devices 100 maycommunicate over a network, such as a local-area network (LAN), such asa company Intranet, a metropolitan area network (MAN), or a wide areanetwork (WAN), such as the Internet or the World Wide Web. In someembodiments, there are multiple networks between the computing devices100. The network may be any type and/or form of network and may includeany of the following: a point to point network, a broadcast network, awide area network, a local area network, a telecommunications network, adata communication network, a computer network, an ATM (AsynchronousTransfer Mode) network, a SONET (Synchronous Optical Network) network, aSDH (Synchronous Digital Hierarchy) network, a wireless network and awireline network. In some embodiments, the network may comprise awireless link, such as an infrared channel or satellite band. Thetopology of the network may be a bus, star, or ring network topology.The network and network topology may be of any such network or networktopology as known to those ordinarily skilled in the art capable ofsupporting the operations described herein. The network may comprisemobile telephone networks utilizing any protocol or protocols used tocommunicate among mobile devices, including AMPS, TDMA, CDMA, GSM, GPRSor UMTS. In some embodiments, different types of data may be transmittedvia different protocols. In other embodiments, the same types of datamay be transmitted via different protocols.

In one embodiment, the system may include multiple, logically-groupedcomputing devices 100. In these embodiments, the logical group ofservers may be referred to as a farm 38 or as a pool of computingdevices 100. In some of these embodiments, the computing devices 100 maybe geographically dispersed. In some cases, a farm 38 may beadministered as a single entity. In other embodiments, the server farm38 comprises a plurality of server farms 38. In one embodiment, theserver farm executes one or more applications on behalf of one or moreclient computing devices.

The computing devices 100 within each farm 38 can be heterogeneous. Oneor more of the computing devices 100 can operate according to one typeof operating system platform (e.g., WINDOWS NT, manufactured byMicrosoft Corp. of Redmond, Wash.), while one or more of the othercomputing devices 100 can operate on according to another type ofoperating system platform (e.g., Unix or Linux).

The computing device 100 of each farm 38 may not need to be physicallyproximate to another server 106 in the same farm 38. Thus, the group ofservers 106 logically grouped as a farm 38 may be interconnected using awide-area network (WAN) connection or a metropolitan-area network (MAN)connection. For example, a farm 38 may include servers 106 physicallylocated in different continents or different regions of a continent,country, state, city, campus, or room. Data transmission speeds betweenservers 106 in the farm 38 can be increased if the servers 106 areconnected using a local-area network (LAN) connection or some form ofdirect connection.

As shown in FIG. 2C, the system includes multiple computing devices 100,each of which makes at least one physical processor 221 available forcomputing and one of which has been designated as a master computingdevice. In contrast to the embodiment depicted in FIG. 2B, in which eachcontrol operating system 105 b on each computing device 100 a transmitsdata to each control operating system 105 b, FIG. 2C depicts anembodiment in which control operating systems 105 a and 105 bcommunicate with the master computing device 100 c and its controloperating system 105 c. In this embodiment, the master computing device100 c maintains a unified view of resources available for use by eachcomputing device 100 in a pool of computing devices. In someembodiments, the master computing device 100 c compiles an enumerationof resources available throughout the pool of computing devices anddetermines a common subset of resources available across the pool. Inother embodiments, the master computing device 100 c compiles anenumeration of functionality provided by a type of resource madeavailable by each computing device in the pool of computing devices (forexample, by enumerating the functionality provided by each physicalprocessor made available by each computing device 100) and determines acommon subset of functionality made available by resources in the pool.In some embodiments, the computing devices 100 in a plurality ofcomputing devices 100 elect one of the computing devices to provide thefunctionality of a master computing device 100 c. In other embodiments,the computing devices 100 in a plurality of computing devices 100 electa subset of the computing devices to provide the functionality of amaster computing device. In still other embodiments, the computingdevices 100 exchange state data with the master computing device 100 cto provide each computing device 100 with a snapshot of data stored bythe master computing device 100 c; in this embodiment, should the mastercomputing device 100 c fail and another computing device 100 n beelected as a new master computing device, the newly-elected computingdevice 100 n may access the snapshot of data to reduce the impact of thefailover process.

Referring now to FIG. 3, a flow diagram depicts one embodiment of amethod for facilitating virtualization of a heterogeneous processorpool. In brief overview, the method includes identifying a plurality ofphysical processors available for computing (302). The method includesdetermining a set of flags, each of the set of flags identifying a typeof functionality provided by each of a subset of the plurality ofphysical processors (304). The method includes allocating, by ahypervisor to at least one virtual machine, access to one of the subsetof the plurality of physical processors (306).

Referring now to FIG. 3, and in greater detail, a plurality of physicalprocessors available for computing are identified (302). In oneembodiment, a processor allocation component 210 identifies theplurality of physical processors available for computing. In anotherembodiment, the hypervisor 101 identifies the plurality of physicalprocessors available for computing. In still another embodiment, acontrol operating system 105 queries the hypervisor to identify anyphysical resources made available by the computing device 100 and thecontrol operating system 105 transmits the identified physical resourcesto the processor allocation component 210. In yet another embodiment, atools stack 104 provides functionality for querying the hypervisor andtransmits to the processor allocation component 210 the identifiedphysical resources. In some embodiments, the tools stack 104 queries akernel on the computing device 100 to identify a plurality of physicalprocessors available for computing.

A set of flags is determined, each of the set of flags identifying atype of functionality provided by each of a subset of the plurality ofphysical processors (304). In one embodiment, the set of flags is asubset of a set of flags; for example, a superset of flags may includeflags identifying functionality provided by only one of the physicalprocessors 221 a as well as flags identifying functionality provided byboth the physical processor 221 a and a second physical processor 221 d,and the set may include only the flags identifying the functionalityprovided by both of the physical processors 221 a and 221 d. In anotherembodiment, an entire superset of flags identifies functionalityprovided by each of a plurality of physical microprocessors; in such anembodiment, the set may include all of the flags.

In some embodiments, a control operating system 105 c on a mastercomputing device 100 c receives, from a control operating system 105 a,a set of flags identifying functionality provided by a physicalprocessor 221 a available on a computing device 100 a and the mastercomputing device 100 c receives, from a control operating system 105 b,a set of flags identifying functionality provided by a physicalprocessor 221 b available on a computing device 100 b. A componentexecuting within the control operating system 105 c—such as the processallocation component 210 c—may determine a common set of functionalityprovided by both the physical processor 221 a and the physical processor221 b; the common set may be the entire combined set of flags or asubset of the combined sets of flags. The control operating system 105 cmay, for example, transmit the determined common set of flags to acontrol operating system 105 b on the computing device 100 b for use inallocating resources to a virtual machine 106 b that may eventuallymigrate from the computing device 100 b to the computing device 100 a.In some embodiments, when a new computing device 100 d is added to orremoved from the pool of computing devices, or when a new physicalprocessor 221 becomes available or is no longer available, the controloperating system 105 c determines an updated set of flags and transmitsthe updated set of flags to each of the computing devices 100 in thepool of computing devices.

In other embodiments, a control operating system 105 a on the computingdevice 100 a and a control operating system 105 b on the computingdevice 100 b communicate directly with each other instead of via amaster computing device 100 c. For example, as described above inconnection with FIG. 2B, the control operating systems 105 a, 105 b maycommunicate through the hypervisors 101 a, 101 b, or exchange data viause of a storage element 250. In one of these embodiments, each controloperating system 105 determines the set of flags.

A hypervisor allocates, to at least one virtual machine, access to oneof the subset of the plurality of physical processors (306). In oneembodiment, a hypervisor 101 receives, from a control operating system105, an identification of the determined set of flags. In anotherembodiment, the hypervisor 101 receives the identification of thedetermined set of flags with an instruction to execute a virtual machine106. In still another embodiment, the hypervisor 101 receives theidentification of the determined set of flags with an instruction toallocate to a virtual processor within a virtual machine 106 access to aphysical processor 221 within the subset of physical processors. In yetanother embodiment, the hypervisor 101 provides the virtual processor inthe at least one virtual machine, the virtual processor implementingonly functionality identified by the set of flags. For example, thehypervisor 101 may generate a virtual processor 132 capable ofproviding, to a resource executing within the virtual machine 106 (suchas a guest operating system 110) only the identified functionality.

In some embodiments, the hypervisor 101 intercepts a request by acomponent within the virtual machine 106 (such as the virtual processor132 or the guest operating system 110) for access to functionality notidentified by a flag in the determined set of flags and the hypervisor101 responds to the request with an indication that the functionality isnot available from the allocated physical processor. In one of theseembodiments, the allocated physical processor in the subset of theplurality of physical processors does provide the requestedfunctionality—for example, the physical processor may implement afunctionality identified by a superset of the determined set offlags—but not all physical processors in the subset provide thefunctionality. Therefore, preventing the virtual machine 106 fromaccessing the functionality not available from all of the physicalprocessors results in execution of a virtual machine 106 that maymigrate between computing devices providing access to heterogeneousphysical processors.

In some embodiments, the identification and determination occur as partof a process for executing a virtual machine 106. In one of theseembodiments, for example, a control operating system 105 on a computingdevice 100 may retrieve an identification of a plurality of physicalprocessors available from one or more computing devices 100, determinethe set of flags identifying functionality provided by each of theplurality of physical processors, and instruct a hypervisor 101 on thecomputing device 100 to execute a virtual machine 106 and to allocatevirtual resources to the virtual machine 106, the virtual resourcesimplementing only the functionality identified by the subset of flags.In other embodiments, by determining a set of flags identifyingfunctionality common across a plurality of a physical processors, and byallocating, to a virtual machine 106, access to only the identifiedfunctionality, the virtual machine 106 will not attempt to accessfunctionality that is provided by a first physical processor on a firstcomputing device but not by a second physical processor on a secondcomputing device; in such an embodiment, the virtual machine 106 may bemigrated between the two computing devices without errors arising froman attempt to access unsupported functionality.

In some embodiments, at least one of the plurality of physicalprocessors provides additional functionality not identified by a flag inthe determined set of flags. In one of these embodiments, by onlyproviding access to the common subset of functionality made available byeach of the plurality of physical processors—or each of a subset of thephysical processors including the at least one physical processorproviding the additional functionality—a virtual machine 106 allocatedaccess to the at least one may not receive an identification of theadditional functionality and may not utilize the additionalfunctionality. In another of these embodiments, therefore, the systemmay provide a mechanism by which a user may choose whether a virtualmachine 106 should be allocated access to the common set offunctionality—improving ease of migration in environments in which thevirtual machine 106 may migrate from one computing device to another—orwhether the virtual machine 106 should be allocated access to all of thefunctionality provided by a particular physical processor, resulting inenhanced performance by the virtual machine 106 utilizing the additionalfunctionality. In such an embodiment, the system determines the set offlags responsive to a command received from a user. In still another ofthese embodiments, a user, such as an administrator may select improvedease of migration for a first virtual machine 106 a, while selectingimproved performance for a second virtual machine 106 b. In still evenanother embodiment, allowing a user to selectively apply the mechanismsdescribed herein provides the user with greater control and flexibilityin managing a plurality of virtual machines. In yet another embodiment,the system includes a user interface allowing the user to specifycustomized preferences for each virtual machine; for example, thecontrol operating system 105 may provide the user interface.

It should be understood that the systems described above may providemultiple ones of any or each of those components and these componentsmay be provided on either a standalone machine or, in some embodiments,on multiple machines in a distributed system. In addition, the systemsand methods described above may be provided as one or morecomputer-readable programs embodied on or in one or more articles ofmanufacture. The article of manufacture may be a floppy disk, a harddisk, a CD-ROM, a flash memory card, a PROM, a RAM, a ROM, or a magnetictape. In general, the computer-readable programs may be implemented inany programming language, such as LISP, PERL, C, C++, C#, PROLOG, or inany byte code language such as JAVA. The software programs may be storedon or in one or more articles of manufacture as object code.

Having described certain embodiments of methods and systems forfacilitating virtualization of a heterogeneous processor pool, it willnow become apparent to one of skill in the art that other embodimentsincorporating the concepts of the disclosure may be used. Therefore, thedisclosure should not be limited to certain embodiments, but rathershould be limited only by the spirit and scope of the following claims.

What is claimed is:
 1. A computer-implemented method for facilitatingvirtualization of a heterogeneous processor pool, the method comprising:identifying a plurality of physical processors available for computing;determining a common processor instruction set for a set offunctionality supported across each physical processor in the identifiedplurality of physical processors, wherein at least one physicalprocessor in the plurality of physical processors provides additionalprocessor instructions for additional functionality that is not in thedetermined common set of functionality; and providing, by a hypervisor,to at least one virtual machine, a virtual processor implementing onlythe common processor instruction set for the set of functionality. 2.The method of claim 1, wherein identifying further comprises identifyinga plurality of heterogeneous physical processors distributed across aplurality of physical machines.
 3. The method of claim 1, whereindetermining further comprises determining a set of flags, each flag inthe set of flags identifying a type of functionality provided by atleast one of the plurality of physical processors and determining thecommon processor instruction set for the set of functionality is basedon a common set of flags.
 4. The method of claim 3, wherein the type offunctionality identified by at least one flag is an instructionextension.
 5. The method of claim 3, wherein the type of functionalityidentified by at least one flag is one of a multimedia extensionfunctionality and a parallel execution functionality.
 6. The method ofclaim 1, wherein determining the common processor instruction set forthe set of functionality further comprises determining the common set offunctionality responsive to a command received from a user.
 7. Themethod of claim 6, wherein the command received indicates whether avirtual machine should be allocated access to the common set offunctionality or whether the virtual machine should be allocated accessto all of the functionality provided by a particular physical processor.8. The method of claim 1, further comprising: identifying a change inthe plurality of physical processors available for computing, whereinthe change is one of i) a physical processor ceasing to be available andii) an additional physical processor becoming available; and determininga revised common set of functionality supported across each physicalprocessor in a revised plurality of physical processors available forcomputing, responsive to the identified change.
 9. A system forfacilitating virtualization of a heterogeneous processor pool, thesystem comprising: a plurality of physical processors available forcomputing; a hypervisor configured to determine a common processorinstruction set for a set of functionality supported across eachphysical processor in the plurality of physical processors and provide,to at least one virtual machine, a virtual processor implementing onlythe common processor instruction set for the set of functionality,wherein at least one physical processor in the plurality of physicalprocessors provides additional processor instructions for additionalfunctionality that is not in the determined common set of functionality.10. The system of claim 9, wherein the system further comprises aprocessor allocation component configured to identify a plurality ofheterogeneous physical processors distributed across a plurality ofphysical machines.
 11. The system of claim 9, wherein the system furthercomprises a processor allocation component configured to determine a setof flags, each flag in the set of flags identifying a type offunctionality provided by at least one of the plurality of physicalprocessors and determining the common processor instruction set for theset of functionality is based on a common set of flags.
 12. The systemof claim 11, wherein the type of functionality identified by at leastone flag is an instruction extension.
 13. The system of claim 11,wherein the type of functionality identified by at least one flag is oneof a multimedia extension functionality and a parallel executionfunctionality.
 14. The system of claim 9, wherein the system furthercomprises a process allocation component configured to identify aplurality of heterogeneous physical processors distributed across aplurality of physical machines and to determine the common processorinstruction set responsive to a query.
 15. The system of claim 9,wherein the hypervisor is further configured to intercept a request by acomponent within the virtual machine for access to functionality notwithin the implemented common set of functionality and to respond to therequest with an indication that the functionality is not available. 16.The system of claim 9, wherein the hypervisor is further configured todetermine a revised common set of functionality supported across eachphysical processor in a revised plurality of physical processorsavailable for computing, responsive to an identified change, wherein thechange is one of i) a physical processor ceasing to be available and ii)an additional physical processor becoming available. 17.Computer-readable non-transitory storage media storingprocessor-executable instructions, which, when executed by one or moreprocessors, cause the one or more processors to: identify a plurality ofphysical processors available for computing; determine a commonprocessor instruction set for a set of functionality supported acrosseach physical processor in the identified plurality of physicalprocessors, wherein at least one physical processor in the plurality ofphysical processors provides additional processor instructions foradditional functionality that is not in the determined common set offunctionality; and provide, to at least one virtual machine, a virtualprocessor implementing only the common processor instruction set for theset of functionality.
 18. The media of claim 17, wherein theinstructions further comprises instructions to determine a set of flags,each flag in the set of flags identifying a type of functionalityprovided by at least one of the plurality of physical processors anddetermining the common processor instruction set for the set offunctionality is based on a common set of flags.
 19. The media of claim18, wherein the type of functionality identified by at least one flag isone of an extended instruction functionality and a parallel executionfunctionality.
 20. The media of claim 17, wherein the instructionsfurther comprises instructions to: identify a change in the plurality ofphysical processors available for computing, wherein the change is oneof i) a physical processor ceasing to be available and ii) an additionalphysical processor becoming available; and determine a revised commonset of functionality supported across each physical processor in arevised plurality of physical processors available for computing,responsive to the identified change.